The purpose of this Master's thesis is to explore smart contracts, underlaying blockchain tehnology and to build a smart contract for sellings goods that is entirely decentralized along with dispute process. In the first part, Ethereum global platform for building decenralized applications is explained along with all the functionalities of Etherum such as Ether money, making transaction on Ethereum blockchain, wallets, etc. After understanding Ethereum blockchain and it's principles, the understanding of smart contracts is going to be much easier. Solidity is the programming language used to create smart contracts on Ethereum network. After learning about Ethereum, blockchain, and smart contracts the development process of creating a smart contract for selling goods in Remix IDE is explained along with the creation of user-interface. After smart contract for selling goods is created and tested in Remix IDE, the development of UI can begin. All the functions of smart contract for selling goods are described in detail along with React UI components for executing functions of smart contract on Ethereum blockchain. In the end both panels for buyer and seller are described along with all the functionalities they bring. Besides main panels, there are separate panels for buyer and seller that are used to solve disputes between the two parties.